Overfishing on Caribbean and Pacific Overfishing on Caribbean and Pacific Coral Reefs and Potential SolutionsCoral Reefs and Potential Solutions

Alan FriedlanderAlan FriedlanderNOAA/NOS/NCCOS/CCMA NOAA/NOS/NCCOS/CCMA –– Biogeography BranchBiogeography Branch

Oceanic Institute, Waimanalo, HawaiiOceanic Institute, Waimanalo, Hawaii

• Declines in: – abundance – size – reproductive output

• Changes in:– sex ratio– behavior & distribution

• Changes in:– Trophic structure– Predator-prey dynamics– Habitat – Algal & inverts– Phase-shift

Direct Effects Ecosystem Effects

Increases in Fishing Capacity in the US Virgin Islands

1930s1958

1980s Today

1960 – Greater Lameshur Bay 1989-2000 – Monitoring Data

Snappers7%Herbivores

40%

Groupers3%

Secondary Consumers31%

Historical biological data in Virgin Islands provide Historical biological data in Virgin Islands provide earlier baseline for comparison w/ recent monitoringearlier baseline for comparison w/ recent monitoring

Beets and Friedlander in review

Groupers15%

Snappers9%

Secondary Consumers36%

Herbivores35%

OtherPredators

5%

OtherPredators15%

Changes in Grouper Species - U.S. Virgin Islands

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Coney

Rock Hind

Tiger

Yellow Fin

Red Hind

Nassau

Proportion of species observed

1958-601989-2000

290

300

310

320

330

340

350

360

370

380

390

1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003

Year

Ave

rage

Tot

al L

engt

h (m

m)

OPEN CLOSED

Spawning aggregation closure for red hind in the US Virgin Islands resulted in increased fish size and more

males over time

Beets & Friedlander 1999, Sladek Nowlis & Friedlander 2005

Changes in Max. Size of Important Species in Virgin Islands National Park from 1989 to 2006

Friedlander and Beets 2008 % change in max. size (1989 to 2006)-30 -25 -20 -15 -10 -5 0

Spanish Hogfish

Mahogany Snapper

Grey Snapper

Graysby

Red Hind

1900 1920 1940 1960 1980 20000

5x103

10x103

15x103

20x103

100x103

200x103

300x103

400x103

500x103

600x103 Ulua - Jacks(Carangidae)

1900 1920 1940 1960 1980 20000

5000

10000

15000

20000

25000

30000

35000

Moi(Polydactylus sexfilis)

1900 1920 1940 1960 1980 20000

50x103

100x103

150x103

250x103

300x103

350x103

'o'io - Bonefish(Albula spp.)

1900 1920 1940 1960 1980 20000

10x103

20x103

30x103

40x103

50x103

60x103

kumu - Whitesaddle Goatfish(Parupeneus porphyreus)

Commercial Landings (lbs) for Select Targeted Fisheries Species in Hawai‘i

Friedlander et al. 2005

0.00

0.05

0.10

0.15

0.20

0.25

0.30

15 19 23 27 31 35 39 43 47 51 55

FemalesHermaphroditesMalesJuveniles

1962-68

0.00

0.05

0.10

0.15

0.20

0.25

15 19 23 27 31 35 39 43 47 51 55Length (cm)

FemalesHermaphroditesMalesJuveniles

1999

Friedlander & Ziemann 2003

Pro

porti

on o

f tot

alChange in Size and Sex Ratio of Harvested Change in Size and Sex Ratio of Harvested MoiMoi((PolydactylusPolydactylus sexfilissexfilis) on Oahu since the 1960) on Oahu since the 1960’’ss

Sex 1960s 1999 SizeJuv 6.4% 39.70% ***M 52.3% 33.80% ***H 17.8% 10.30% ***F 23.5% 16.20% ***

Loss of Herbivores lead to Algal-dominated Reef

Friedlander et al. 2008

Herbivore (>15 cm) biomass (t/ha)0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40

Mac

roal

gae

cove

r (%

)

0

5

10

15

20

25

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Apex predators Primary consumers Other secondary consumersConsumer category

Mea

n bi

omas

s (m

T/he

ctar

e

Northwestern Hawaiian Islands

Main Hawaiian Islands

Comparison of feedings groups in the MHI & NWHI

Friedlander& DeMartini 2002

P<0.05 P<0.05 P<0.05

7012%

83%55%

Status of 55 MHI Reef Fish Stocks relative to Unfished, Virgin Stocks in the NWHI

+

Friedlander et al. 2008

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

5 10 15 20 25 30 35 40 45 50 55 65 70 75 80 85 90 95 100+

Biomass status (% of NWHI)

Freq

uenc

y

Critical (42%)

Belowdesiredlevels(11%) Not

overfished(13%)

Hyper-abundant

(2%)

Depleted (33%)

KINGMAN REEF PALMYRA ATOLL

TABUAERANKIRITIMATI

0 people 10 people

6-8,000 people2,500 people

Hawaii

Declines in Fish Biomass across a Gradient of Human Impact in the Line Islands

0

1

2

3

4

5

6

Kingman Palmyra Tabuaeran Kiritimati

Bio

mas

s (t

ha-1

)

Apex predatorsSecondaryHerbivore

Population: 0 ~10 2,500 ~7,000

Sandin et al. 2008, DeMartini et al. 2008

Advances in fishing Advances in fishing technologytechnology

have reduced natural have reduced natural refugesrefuges

Percent Difference in Fish Assemblage Characteristics between MPAs and Open Areas in Hawaii

0%

100%

200%

300%

400%

Biomass No. > 20 cm Number ofindiv.

Species Diversity

Perc

ent d

iff. b

etw

een

MPA

s an

d op

en a

reas

Friedlander et al. 2006; 2007a 2007b

Recognize natural rhythms Recognize natural rhythms

Do not disturb basic renewal processesDo not disturb basic renewal processes

Monitor cues (moon, season, habitat)Monitor cues (moon, season, habitat)

Resource knowledgeResource knowledge

–– IntimacyIntimacy

–– AncestorsAncestors

Traditional Hawaiian Marine Traditional Hawaiian Marine Resource UseResource Use

Mo’omomi Fish Spawning Calendar (2000) Red = Peak Spawning Months, Orange = Other Spawning Months

Friedlander et al 2002, Poepoe et al 2003

Comparison of Fish Biomass in Areas under Various Management Regimes in Hawaii

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

No-take Customarystewardship

Partial protection Open access

mT/

hect

are

A A B B

F = 7.947P < 0.001

Adapted from Friedlander et al. 2003

Community based

• Overfishing has led to:– Reduced abundance, size & sex ratios of key sp.– Loss of ecosystem function

• Loss of top-down control by predators• Loss of herbivores lead to algal overgrowth

• MPAs highly effective in conserving populations• Traditional community-based management

effective in appropriate locations